Service engine light on 96 Buick Century

Has anyone every bought a kit to recharge an A/C system r134? Is it as simple as they say and what's to watch out for? Thanks

Hello, I am a home mechanic in training. I have a '93 Honda Civic DX coupe, 5 speed manual transmission with 150k miles. It was in southern California for most of its life, but has spent the last 3 years in hot and humid Alabama. A couple summers ago, the A/C compressor failed and vented most of the R12 refrigerant. The symptoms were white mist from the A/C vents, liquid all over the compressor, and the compressor would stall the car most of the time I turned it on. My very limited research into repair costs suggested it was going to cost more than half the value of the car to have someone fix it, so I decided to try on my own. I had no prior A/C experience, but I had a friend who did. I had the system evacuated (I guess it still had some pressure) and replaced the compressor and expansion valve. As part of the process, I also flushed the system since I was changing over to R134a. After reassembly, I sucked down the system and then filled it with R134a. The recharge instructions were inconsistent, some saying to keep the can upright, and some saying to turn it upside down when charging. I opted for the former. For over a year, the A/C worked okay, but was not very cold. Then, many months ago, it went out completely while I was driving. Shortly after noticing that the air was no longer cool (it was a hot day), I rolled down my windows. I then smelled burning and noticed smoke coming from my car. I pulled off the road and looked around the A/C compressor. It seemed like it had leaked liquid, but nothing else was obvious. I went home and hooked up my A/C gauges. The suction pressure was high and the discharge pressure was low, but they were not equal and they fluctuated a lot as the compressor ran. I decided it may have been a bad charge since I had not had the refrigerant can upside down during the last charging a year prior. So, I evacuated the system and recharged it "properly" with the can upside down. It worked fine, and the air was much cooler than before. I thought I had fixed the problem. Today, however, we had the hottest day of the year. I was driving home and the A/C went out again (the air from the vents ceased being cold). I also noticed that with the A/C on, the car was making a surging noise on a couple seconds, off a couple seconds, repeated over and over. I turned off the A/C and went home. I hooked up my gauges and found that with the A/C on, the suction and discharge pressures were equal at about 150 psi and did not change whether or not the compressor was running. With the A/C on, the compressor was cycling on and off every couple seconds (the surging mentioned above) and was straining the engine almost enough to stall it. I evacuated the system and took the compressor off. I took it apart (partially) to look for anything obviously damaged and didn't find anything. I put it back together, evacuated the system again, and recharged it with a can of R134a. Unfortunately, it is still doing the same thing. The compressor cycles on and off straining the engine A LOT. The suction and discharge pressures are still equal, but at 70 psi now, regardless of whether or not the compressor is running. The air seemed to get a little cool, but not much. Can any one tell me what they think is wrong? I am very mechanically inclined and want to try to fix this. I cannot afford to pay to have it fixed unless imperative. Thanks a lot, Josh